pitch warble using spark guitar amplifier

[LAguitar]

We are brand new to reaper and we are using a Spark guitar amplifier as our interface. We just tried our first recording, but the playback sounds kind of warbly. Almost like there's a pitch modulation. It's not an echo from the monitor, its definitely a warble/pitch modulation. Any ideas on what this is? Thanks!

[DVDdoug]

I don't know, but The only way to accidentally get a pitch shift is is to change/vary the sample rate.

...Varying the sample rate would also be a good way to do it intentionally.

[LAguitar]

Okay! Thank you. Is that something I can do on the speaker or in Reaper itself? How do I change the sample rate? Can I do that once the recording is already made, or is it a setting that I should set before recording?